Phytoplankton communities of North African wetland lakes: the CASSARINA Project

Seasonal variations in phytoplankton species composition (frequencies) and densities (cell numbers) in nine North African coastal lakes selected in Morocco (Merja Sidi Bou Rhaba, Zerga and Bokka), Tunisia (Chitane, Ichkeul and Korba lakes) and Egypt (Edku, Burullus and Manzala lakes) were investigated during 1998. The main aim was to provide gase-line information about overall phytoplankton diversity and how phytoplanktoncharacteristics differ between these contrasting aquatic systems.Water samples were collected at approximately three monthly intervals and phytoplankton analysis revealed marked seasonal and spatial differences in the quantitative and qualitative composition of the communities at each site. The Egyptian lakes generally had larger crops (Manzala and Burullus had mean crop densities of more than 104 cells ml^–1) but in the western North African sites only Korba and Sidi Bou Rhaba had closely comparable densities. Algae belonging to Bacillariophyceae, Chlorophyceae, Chrysophyceae, Cyanophyceae, Dinophyceae and Euglenophyceae were recorded. Taxa representative of all these algal groups occurred in two lakes (Korba and Manzala) but at the other seven sites only some of the groups were present.The Chlorophyceae was the most dominant group in lakes Burullus, Manzala, Korba and Sidi Bou Rhaba whereas Bacillariophyceae were dominant in lakes Zerga, Bokka and Edku. In Ichkeul and acidic Chitane the Dinophyceae and the Cyanophyceae were the dominant groups, respectively. The maximum percentage of Euglenophyceae occurred in Edku Lake but this group was absent in Sidi Bou Rhaba and Ichkeul. Cyanophyceans were present in significant numbers in all investigated lakes except in Ichkeul. A total of fifty-three genera were recorded, 17 of Chlorophyceae, 18 of Bacillariophyceae, 11 of Cyanophyceae, 3 of Chrysophyceae, 2 of Euglenophyceae and 2 of Dinophyceae. The maximum number of species (34) occurred in Burullus Lake and the minimum (6) in Ichkeul Lake. Only one lake (acidic Chitane) possessed species indicative of oligotrophic conditions. The Nile Delta lakes were the most species diverse sites.The phytoplankton communities of the nine North African lakes were composed entirely of cosmopolitan species but with one new species (Cyclotella choctawatcheeana) was recorded for the region. The data presented provide a contemporary account of the levels of algal diversity present in these sites at the end of the 20th century. The relevance of phytoplankton communities to assessment of lake status and future monitoring studies in the region is emphasised.     

Effect of fluctuations in water level on phytoplankton development in three lakes of the Paraná river floodplain (Argentina)

The effect of fluctuations in water level on phytoplankton development (abundance, biomass, size structure, taxonomic composition, species diversity and rate of community compositional change) in three vegetated lakes of the Paraná River floodplain (27° 27′?S; 58° 55′?W) were studied. Between September 1995 and June 1996 there were two inputs of lotic water. Ordering of physical and chemical parameters (Principal Component Analysis) allowed the differentiation of two phases: I) without lotic influence (limnophase) and II) with lotic influence (potamophase). Two-hundred fifty-eight algal taxa were identified, of which Euglenophyceae showed the highest number of taxa (65% of total). Small Chlorophyceae and Cryptophyceae (C-strategists) predominated in density in both periods. During potamophase, the input of nutrients from a flood event produced an increase in algal biomass and a shift in phytoplankton composition from a Chlorophyceae (C-strategists), to a Cyanophyceae and Euglenophyceae (S-strategists), dominated comunity. Bacillariophyceae, Chrysophyceae, Dinophyceae and Xanthophyceae were best represented during limnophase. All phytoplankton attributes showed significant differences between phases (limnophase vs potamophase) but not among lakes. These results support the hypothesis that hydrology (floods) clearly exerts an overall impact on the phytoplankton community composition in lakes of the Paraná River floodplain. Hydrology effects the lake water chemistry, conditioned by the isolation time prior to a flood, the horizontal dragging and exchange of algae during floods, and the water residence time and aquatic vegetation coverage.     

The phytoplankton of the internal Gulf of Olbia (North-East Sardinia) between July 1992 and July 1993

Abstract

The density variations and phytoplankton structure of the internal Gulf of Olbia (north-east Sardinia) from July 1992 to July 1993 are described.

The most important class was the Bacillariophyceae, because it accounted for the maximum values and because it dominated over about one-third of the study cycle. The picoplankton was present practically all the year round with the greatest development from September to March. Prymnesiophyceae, Dinophyceae, Cyanophyceae and Euglenophyceae were found more numerously in summer and autumn 1992 than in the rest of the year, while Bacillariophyceae, Chlorophyceae and Chrysophyceae were mostly found in spring and summer 1993.

Among the 16 species that expressed the highest mean yearly density values (greater than 1×10⁴ cell I^-1), 10 were Bacillariophyceae, 2 Dinophyceae, 3 Chrysophyceae and 1 Chlorophycea. The Bacillariophyceae have also been the dominant class in floristic terms (49 taxa on 95 total), followed by the Dinophyceae (26), the Chlorophyceae (5), the Chrysophyceae (5), the Prymnesiophyceae (4), the Prasinophyceae (2), the Euglenophyceae (2) and the Cyanophyceae (2).     

Contrasting roles of water chemistry, lake morphology, land-use, climate and spatial processes in driving phytoplankton richness in the Danish landscape

Understanding of the forces driving the structure of biotic communities has long been an important focus for ecology, with implications for applied and conservation science. To elucidate the factors driving phytoplankton genus richness in the Danish landscape, we analyzed data derived from late-summer samplings in 195 Danish lakes and ponds in a spatially-explicit framework. To account for the uneven sampling of lakes in the monitoring data, we performed 1,000 permutations. A random set of 131 lakes was assembled and a single sample was selected randomly for each lake at each draw and all the analyses were performed on permuted data 1,000 times. The local environment was described by lake water chemistry, lake morphology, land-use in lake catchments, and climate. Analysis of the effects of four groups of environmental factors on the richness of the main groups of phytoplankton revealed contrasting patterns. Lake water chemistry was the strongest predictor of phytoplankton richness for all groups, while lake morphology also had a strong influence on Bacillariophyceae, Cyanobacteria, Dinophyceae, and Euglenophyceae richness. Climate and land-use in catchments contributed only little to the explained variation in phytoplankton richness, although both factors had a significant effect on Bacillariophyceae richness. Notably, total nitrogen played a more important role for phytoplankton richness than total phosphorus. Overall, models accounted for ca. 30% of the variation in genus richness for all phytoplankton combined as well as the main groups separately. Local spatial structure (<30 km) in phytoplankton richness suggested that connectivity among lakes and catchment-scale processes might also influence phytoplankton richness in Danish lakes.     

Phosphatase activity in relation to phytoplankton composition and pH in Swedish lakes

SUMMARY. 1. Potential phosphatase activity and phytoplankton from several lakes of different character were compared in order to evaluate the importance of lake water pH and phytoplankton composition for the activity and pH optimum of lake water phosphatases.
2. In oligotrophic lakes, in which phytoplankton biomass was most often dominated by Ochromonadaceae spp., optimum phosphate activity was found at pH values <6. In eutrophic lakes, where species of Cyanophyceae and Bacillariophyceae dominated the phytoplankton biomass, optimum phosphatase activity was found at pH 7.5 or 8.5.
3. The pH optimum of phosphatase activity often differed from the corresponding lake water pH.
4. Experimental variation in phosphorus availability resulted in predictable changes in phosphatase activity. However, specific phosphatase activity, calculated per biomass of phytoplankton, was dependent on plankton species composition.     

Phytoplankton species abundance in Lake Kasumigaura (Japan) monitored monthly or biweekly since 1978

This data paper reports the abundance of phytoplankton species in monthly or biweekly samples collected from May 1978 through March 2010 at two stations on Lake Kasumigaura, a shallow lake that is the second-largest lake in Japan. The data set of quantitatively over several decades is unique among the available published data papers concerning lakes or plankton and continues to be freely available. The monitoring has been performed as a component of the Lake Kasumigaura Long-term Environmental Monitoring program, conducted by the National Institute for Environmental Studies since 1977. The data set details 173 phytoplankton species (or taxa), which can be identified by using an optical microscope and records their abundance. The abundance of each species is expressed in units of volume (??m³) per milliliter of lake water. This approach allows quantitative comparisons among taxa because the cell size of phytoplankton varies by several orders of magnitude among taxa. The phytoplankton data include 39 species (taxa) of Cyanophyta, 67 Chlorophyceae (Chlorophyta), 3 Prasinophyceae (Chlorophyta), 1 Raphidophyceae (Heterokontophyta), 6 Euglenophyceae (Euglenozoa), 4 Dinophyceae (Dinophyta), 38 Bacillariophyceae (Heterokontophyta), 6 Chrysophyceae (Heterokontophyta), 7 Xanthophyceae (Heterokontophyta), 1 Cryptophyceae (Cryptophyta) and 1 Prymnesiophyceae (Haptophyta). The data have been used for ecological and environmental studies and for studies on lake management.     

Size‐selective feeding on phytoplankton by two morpho‐groups of the small freshwater fish Amblypharyngodon mola

Two morpho‐groups (i.e. small, MGS and big, MGL) of the small freshwater fish Amblypharyngodon mola were studied for their feeding behaviour in the natural environment. Both the morpho‐groups fed on a variety of phytoplankton including Cyanophyceae, Chlorophyceae, Bacillariophyceae and Euglenophyceae. The fish had more Chlorophyceae and Bacillariophyceae in their gut than other phytoplankton. Costello's selectivity plots revealed that the MGS fed on the smaller phytoplankters (2–6 µm in size), whereas the MGL fed on both the small and large (up to 12 µm in size) phytoplankters. The differences in mouth areas between the two morpho‐groups were explained as a possible reason of size‐selective feeding and contribute to overcome gape limitation in A. mola. This is further accompanied by the uniform pore size of the gills (2 µm) in all the morpho‐groups. This study concluded that A. mola exhibits a size‐dependent feeding strategy regulated by gape limitation at the ingestion level. With ontogenetic shifts, flexibility appears to overcome such a limitation in the MGL, having a wider mouth area supported by jaw opening ability.     

Limnological Studies on the River Tigris,Iraq. III. Phytoplankton

Variations in quantity and structure of phytoplankton in the lower 630 km stretch of the Tigris were studied and discussed. The Chlorophyceae generally contributed more genera to the phytoplankton community, and the Bacillariophyceae and Cyanophyceae ranked second and third, respectively. The phytoplankton generally showed considerable local and seasonal variations at the surfaces of the sampling locations.     

Polyphenolics and Energy Content in Phytoplankton: Evidence from a Freshwater Lake

Investigation was carried out in the ancient man-made, shallow, freshwater lake, Lake Krishnasayer, at Burdwan (23°16′N, 87°54′E), India, to note the variations in physico-chemical parameters, nutrients, phytoplankton communities, concentration of phenols and energy content in phytoplanktons during January–December 2006. The lake was represented by 16, 15, 2 and 17 genera of Cyanophyceae, Chlorophyceae, Euglenophyceae and Bacillariophyceae, respectively with significant variation in relative abundance as was revealed through Discriminant Analysis. Wilk’s λ values indicate that nitrate, phosphate, dissolved chlorides and silica, and phenol content were significant (P < 0.05) predictor for such differences. PCA analysis yielded three components explaining more than 68 % of the variations in the data on physico-chemical parameters, nutrients, phenol concentration and energy content of total phytoplankton. The interactions of the environmental variables contribute significantly to the observed variations in the phenol and energy content of the phytoplankton. However, the phenomenon of temporal variation in the total phytoplankton and energy content is accounted as a function of nitrate, phosphate-phosphorous, silicate and organic carbon levels. It is apparent that this quality of phytoplanktons varied with the seasons and thereby influencing the amount of phenol and energy content in the engulfing phytoplanktons. Therefore, adequate allocation is needed regarding nutritional status of phytoplanktons, in respect to the dietary need of aquaculture programme in practice.     

Phytoplankton dynamics in a shallow,hypertrophic reservoir (Lake Arancio,Sicily)

Phytoplankton abundance and composition in the hypertrophic man-made Lake Arancio was analyzed, based on a programme of weekly sampling from May 1990 to November 1991 and supported by measurements of limnological parameters. The highest value of phytoplankton biomass (78 mg l^–1) was observed in October 1990, during a bloom of the desmid Closterium limneticum var. fallax, while the lowest (0.15 mg l^–1) was measured in April 1991. During spring, autumn and winter 1990, species of the genus Closterium dominated the community, in the sequence: C. aciculare, C. limneticum var. fallax, C. limneticum. The summer community was more diverse with the predominance of organisms belonging to Chlorophyceae (Chlamydomonas, Eudorina, Coelastrum) and Cyanophyceae (Microcystis, Anabaena). In spring 1991, there was a long clear-water phase during which small green algae (Ankyra, Oocystis) and cryptomonads dominated. Subsequently, the summer season was characterized by a clear sequence of dominants, drawn, in turns, from species belonging to: Bacillariophyceae, Dinophyceae, Cyanophyceae, Euglenophyceae. The physics of the reservoir and its depth, owing to filling/draining constraints in a summer-arid climate, appeared to play a key role in the dynamics of phytoplankton community.     

Seasonal variation in phytoplankton composition and physical-chemical features of the shallow Lake Doïrani,Macedonia, Greece

Phytoplankton species composition, seasonal dynamics and spatial distribution in the shallow Lake Doïrani were studied during the growth season of 1996 along with key physical and chemical variables of the water. Weak thermal stratification developed in the lake during the warm period of 1996. The low N:P ratio suggests that nitrogen was the potential limiting nutrient of phytoplankton in the lake. In the phytoplankton of the lake, Chlorophyceae were the most species-rich group followed by Cyanophyceae. The monthly fluctuations of the total phytoplankton biomass presented high levels of summer algal biomass resembling that of other eutrophic lakes. Dinophyceae was the group most represented in the phytoplankton followed by Cyanophyceae. Diatomophyceae dominated in spring and autumn. Nanoplankton comprised around 90% of the total biomass in early spring and less than 10% in summer. The seasonal dynamics of phytoplankton generally followed the typical pattern outlined for other eutrophic lakes. R-species (small diatoms), dominant in the early phase of succession, were replaced by S-species (Microcystis, Anabaena, Ceratium) in summer. With cooling of the water in September, the biomass of diatoms (R-species) increased. The summer algal maxima consisted of a combination of H and M species associations (sensu Reynolds). Phytoplankton development in 1996 was subject to the combined effect of the thermal regime, the small depth of mixing and the increased sediment-water interactions in the lake, which caused changes in the underwater light conditions and nutrient concentrations.     

Flood pulse influence on phytoplankton communities of the south Pantanal floodplain, Brazil

Four sites situated on the Pantanal floodplain (Paraguay River and floodplain) were sampled throughout the annual cycle, mainly during the rising water period, with the aim of evaluating the effects of the flood pulse on the composition and population densities of the phytoplanktonic communities. Comprehensive water chemistry data were collected. Eighty-two taxa were found, numerically dominated by Chlorophyceae (23 taxa). Cryptophyceae (principally Cryptomonas brasiliensis) occurred in all samples, and were responsible for 47–58% of the phytoplankton abundance in the studied area. Highest phytoplanktonic population density was at the rising water period, when the limnological changes are most marked as the river water first enters into contact with the floodplain. During this period, when intense decomposition occurs, the Cryptophyceae decreased and the Euglenophyceae increased, except at site 1 (Castelo Lake), where this group were more stable during the year, representing 35–56% of the phytoplankton. In the falling water period (September and October), the phytoplankton was also represented by Bacillariophyceae and Cyanophyceae. In the Pantanal, the great abundance and sometimes dominance of Cryptophyceae, may be due largely to adverse conditions for the development of other groups; the former are adapted to low availability of dissolved nutrients, and high water transparency, such conditions prevailing during the high water period.     

Abundance of algal species in relation to soil types and major crops in cultivated soils of Karnataka state (India)

Summary An attempt was made to study the number of species belonging to Cyanophyceae, Chlorophyceae and Bacillariophyceae in Lateritic, Red and Black soils and also Dry lands (jowar, cotton and wheat) and Wet lands (paddy and sugar cane). Lateritic and black soils had a poor algal flora and in general sandy soils were rich. Cyanophyceae appeared to be more resistant than Chlorophyceae and Bacillariophyceae to desiccation. Part of the Ph.D. Thesis approved by the Karnatak University (1976).     

Limnology of a Sewage Polluted Lake: The Lower Lake (Bhopal,India)

Seasonal and vertical distribution of temperature, pH, dissolved oxygen, free CO₂, alkalinity, nitrate, phosphate and phytoplankton have been studied at the deepest point of the Lower Lake, Bhopal from September 1979 to August 1981. Stratification was noticed in almost all the parameters. Bottom was frequently anoxic. The dominant groups among phytoplankton were Chlorophyceae, Cyanophyceae and Bacillariophyceae.     

Characterization of phytoplankton assemblages in a tropical coastal environment using Kohonen self‐organizing map

This study was aimed at understanding the main abiotic environmental factors controlling the distribution patterns of abundance and composition of phytoplankton (size less than 10 μm) assemblages in the coastal waters of south‐eastern Côte d'Ivoire. Data were collected during two cruises, in January (low‐water period) and October (high‐water period) of 2014. A total of 67 species were identified and assigned to Bacillariophyceae (49%), Cyanophyceae (21%), Chlorophyceae (13%), Euglenophyceae (10%), Dinophyceae (4%) and Chrysophyceae (3%). Three biotic zones (I, IIA and IIB) were distinguishable on a Kohonen self‐organizing map after an unsupervised learning process. The diatom genera Eunotia sp., Navicula sp. and Actinoptychus senarius are significantly associated with I, IIA and IIB biotic zones, respectively. A clear seasonal cum salinity trend was apparent in phytoplankton distribution patterns. Turbidity and nitrate levels were the main abiotic factors controlling phytoplankton distribution in I, the upland tidal regions of the lagoon. In regions along the lagoon–sea continuum, phosphate and turbidity exert the most control during the low‐water season (IIA), while total dissolved solids control phytoplankton distribution during the high‐water season (IIB). These are climate‐sensitive parameters whose concentrations depend on prevailing hydroclimatic processes. Therefore, seasonality can have important consequences on phytoplankton community and inadvertently the productivity of these systems.     

Variation of Phytoplankton in a Tropical Estuary (Vellar Estuary,Bay of Bengal,India)

The phytoplankton species composition and community structure were studied at two stations in the Vellar estuary from January to December, 1983. A total of 117 species of phytoplankton belonging to various groups, namely diatoms (90), dinoflagellates (21), Chlorophyceae (3), Cyanophyceae (2) and silicoflagellates (1) were observed during the study. The species diversity, richness and evenness values varied from 0.7 to 4.2 units/individual, 0.9 to 5.7 and 0.19 to 0.75 respectively. Dominance index values varied between 32.6 and 96.4 during the study period.     

Water quality and plankton periodicity in two contrasting mine lakes in Jos,Nigeria

Water quality and plankton periodicity was studied in two mine lakes near Jos in the younger granite area of Plateau State, Nigeria. The investigation was carried out for 8 months. Transparency, pH and NO₃-N were significantly higher in Lake II while DOM, alkalinity, PO ₄ ^3– -P, BOD and chloride were significantly higher in Lake I. The order of dominance in Lake I was Bacillariophyceae, Cyanophyceae, Chlorophyceae and Dinophyceae while for Lake II; Chlorophyceae, Cyanophyceae, Bacillariophyceae and Dinophyceae. In Lake I the zooplankton in order of dominance were Cladocera, Rotifera, Copepoda, and nauplii and in Lake II Cladocera, Copepoda, Rotifera and nauplii. Although both lakes would seem unproductive based on the PO ₄ ^3– -P and NO ₃ ^– -N levels, Lake I appears more productive than Lake II.     

Some notes about the Intermediate Disturbance Hypothesis and its effects on the phytoplankton of the middle Orinoco river

Phytoplankton behaviour in the middle reaches of the Orinoco river (middle basin) is discussed in relation to the Intermediate Disturbance Hypothesis. Seven sets of samples were taken from two channels formed below the confluence of Meta and Orinoco rivers between September 1990 and August 1991. The Orinoco river channel (ORISMA-1) had many more species than the Meta river channel (ORISMA-2). Chlorophyceae dominated both, except during the rising water period when Bacillariophyceae were dominant. The quantitative dominancy alternates among Chlorophyceae, Bacillariophyceae and Cryptophyceae in both river channels, with minima averaging 14 329 and maxima of 1038 392 cells per liter. The phytoplankton concentration of both river channels is negatively correlated with variability in suspended sediments load. The Shannon-Weaver diversity for ORISMA-1 gives higher values than those from ORISMA-2 and oscillates between 1.37 to 3.52. Disturbances due to increases of water level and high concentration of suspended sediment can be the driving force governing phytoplankton behaviour in large rivers.     

Algicidal properties of Acacia nilotica

The algicidal activity of aqeuous extracts of the pods of Acacia nilotica (L.) Willd. ex Del. was tested in artificial ponds. Algae belonging to the genera Rivularia, Oscillatoria, Spirulina, Chroococcus, Microcystis (Cyanophyceae), Pediastrum, Coelastrum (Chlorophyceae), Spirogyra, Cosmarium, Closterium (Conjugophyceae), Euglena (Euglenophyceae) and Cyclotella (Bacillariophyceae) were successfully controlled with this extract.     

Influence of atypical pluviosity on phytoplankton assemblages in a stretch of a large sub-tropical river (Brazil)

This study aimed to evaluate the influence of alterations in pluviosity and ecological variables on microphytoplankton (> 20 μm) structure (composition, richness, diversity, and abundance) and its biomass (chlorophyll-a), comparing different regions in a stretch of the low Iguaçu River and in some tributaries. Phytoplankton was sampled in 10 stations (5 in Iguaçu River and 5 in tributaries) during a dry period (April/2004) and an atypical rainy period (June/2004). The conductivity showed significant difference among the sampling points. Temperature, dissolved oxygen, pH, silicate, and nitrate showed significant differences between the dry and wet periods. Phytoplankton was composed of 149 taxa, and the most representative class was Chlorophyceae (71 taxa), followed by Bacillariophyceae (35 taxa), and Cyanophyceae (25 taxa). During the rainy period, stations of Iguaçu River showed higher taxa number and total density compared to the tributaries, but the values were similar in the dry period. Tributaries presented higher diversity and equitability in both periods. Except by two stations in Iguaçu River, the higher taxa number, densities and biomass occurred in the dry period, associated to low levels of suspended matter. The canonical correspondence analysis indicated the dominance of Bacillariophyceae and Chrysophyceae in the rainy period related to nitrate and suspended matter. Two other groups were observed in the dry period: one formed by Cyanophyceae, Dinophyceae, and Rhodophyceae, related to temperature and nitrite and other by Euglenophyceae and Chlorophyceae related to total phosphorus and silicate. The groups suggest adequate conditions of the physical, chemical and climatic factors to the establishment of the algae classes. Phytoplanktonic assemblages responded quickly to the environmental regional variations under strong influence of pluviosity, while in the dry period, homogeneity among stations and environmental variables was observed. The importance of climatic events is relevant in ecological studies in a temporal scale.